This invention relates to apparatus for applying hydraulic trailer brakes, and more particularly to apparatus for automatically applying hydraulic trailer brakes in gooseneck trailers.
At the present time there is widespread acceptance and usage of trailers of the type known as gooseneck or fifth wheel-type trailers. As opposed to conventional trailers which connect to structures such as a bumper projecting from the rear of a towing vehicle, gooseneck trailers connect at a point more nearly aligned with the rear wheels of the towing vehicle. For example, a gooseneck trailer is often connected to a ball or similar structure mounted in the bed of a pickup truck and situated above the rear axle of the truck. This relocation of the point of connection of the trailer to the towing vehicle substantially increases the maximum trailer size that can be towed by a particular towing vehicle.
Governmental regulations now require that trailers weighing over 4,000 lbs. be provided with brakes. With respect to gooseneck trailers, the only braking systems that have heretofore been provided for meeting this requirement have comprised electric braking systems and vacuum over hydraulic braking systems. As is well known in the art, both electric braking systems and vacuum over hydraulic braking systems exhibit numerous problems when used in conjunction with gooseneck trailers.
For example, both electric braking systems and vacuum over hydraulic braking systems require an operating handle mounted within a towing vehicle when utilized in conjunction with gooseneck trailers. Both types of braking systems require relatively costly and time consuming maintenance procedures. Electrical braking systems are generally considered to be unsatisfactory and unreliable in operation. Vacuum over hydraulic systems are typically relatively expensive to purchase and install.
The present invention overcomes the foregoing and other difficulties long since associated with the prior art. In accordance with the broader aspects of the invention, apparatus for applying hydraulic trailer brakes includes a post member which is pivotally secured to a towing vehicle. A sleeve member is telescopingly received over the upstanding post member and is pivotally secured to the upper end thereof. An arm extends rearwardly from the sleeve member, and a trailer that is towed by the towing vehicle is secured to the sleeve member. Hydraulic master cylinder apparatus is mounted in the arm for actuation in response to relative pivotal movement between the arm and the upstanding post member. Springs are provided for supporting the weight of the trailer during downhill movement, and shock absorbers are provided for damping relative pivotal movement between the arm and the upstanding post member.
In accordance with more specific aspects of the invention, the bottom of the upstanding post member includes an aperture adapted to receive a ball secured to the towing vehicle. A corresponding aperture is provided in a plate that is pivotally supported at the bottom of the upstanding post member. The apertures in the post member and the plate are initially aligned to receive the ball of the towing vehicle. Thereafter, the plate is moved to a nonaligned postion and is retained in the nonaligned position by a spring loaded pin, whereby the upstanding post member is secured in engagement with the ball.
The hydraulic master cylinder apparatus includes a housing comprising a brake fluid reservoir and a piston which controls the flow of brake fluid into and out of the housing through a port. The housing of the hydraulic master cylinder apparatus is slidably supported on an arm with the piston positioned in engagement with the upstanding post member. A spring is provided for accomodating relative movement between the housing of the hydraulic master cylinder apparatus and the arm upon further relative pivotal movement between the arm and the upstanding post member subsequent to actuation of the piston of the hydraulic master cylinder apparatus.
A lever is pivotally supported on the sleeve member and includes a camming portion positioned for engagement with the upstanding post member. The remote end of the lever is chained to the towing vehicle. Thus, upon accidental disengagement of the upstanding post member from the towing vehicle, the lever is actuated to effect relative pivotal movement between the upstanding post member and the sleeve member, whereupon the hydraulic master cylinder apparatus is actuated to set the trailer brakes. Further pivotal movement of lever causes the camming portion thereof to move over center, whereupon the hydraulic master cylinder apparatus is locked in the actuated condition.